class Solution {
private:
    int F[38] = {0, 1, 1};    
public:
    int tribonacci(int n) {
        for(int i = 3; i <= n; i++)F[i] = F[i - 1] + F[i - 2] + F[i - 3];
        return F[n];
    }
};

/**
 * 2021.8.9
 * 模拟，没啥意思
 */





